320B Excavator Electrical System

ComponentLocation Machine Location 10

G-12

2

Sender-HydOilTemp

 Alternato r

B-11

11

Sensor - A /C Photo

Batteries

I-11

13

Sensor - Engine Speed

Component

 Alternator :132-2156

SENR4757

Wire Wire Number  Color  RD

BU

A

103

RD

Doom Lamp

547

OR

20

105

RD

K ey Sw

548

GY

E ng Shut

549

PK

Aux Hyd - Close

YL

Wiper. A ux P( ark)

D

Sensor - Fuel Level

6

107

RD

D

Sens o r- O v e r olad Wa nri n gD e vi e cOW . . D. A 1

F- 1

D

109

RD

E-8

D

Sensor - P ump Discharge Press

B-8

26

I-11

D

Socket - 12v

D

Solenoid -A -A/C Clutch

A-5

B-6 C-11 I-8

15 27

Cigar Lighter

C-7

A

Solenoid - AC1

Control - O verload Warning D evice O.W.D.

G-5

A

Solenoid - A C2

I-8

39

B-7

A

Solenoid - Aux Pedal On/Off

E-1

39

39

1 3 1

OR

Op rMon Pa e nl VM VMI SB +S w i ct hed

1 14

RD

W ra n i ng Ho nr (F or w a dr )

C537

GN

A/C Photo Sensor +Sig

Converter

C538

OR

A/C Photo Sensor. Sig

124

GN

11

I-8

29

129

BU

Cigar Lighter

607

PK

Fl ood Lamp - Front

E-10

28

135

BU

Aux Ckt

615

YL

Cab Fl ood Lamp/Rops

30

139

OR

39

140

BU

Diode

G-10

7

I-1,2,3

Solenoid - Hammer 2

C

I-6

Solenoid - High Press A3

Solenoid - Level Finish Solenoid - Rl/R2

Ground - Chassis

A-5

E

Solenoid - Start Aid (Atch)

I-12

31

Ground - Platform

D-1

F

Solenoid - Swing Brake

E-10

32

Ground - Relay Panel

G-11

Solenoid - Hyd Lock

F-10

A

E-1 A-8 I-7

G 33 39

D

Solenoid - Travel Speed

A-8

33

Ground - Strap Chassis/Platform

I-5

2

Solenoid - Trenching

A-8

33

Horns

A-2

16

Switch - Air Cleaner

Joystick - Multiswitch

F-3,G-11

Meter - Service

A

C-7

Monitor Motor - Govener Assembly

A 20

F-1

F

Motor - Starter Motor - Upper Wiper Motor - Washer

A-11

20

B-6

22

I-12

Pump - A uto Lubrication (Atch)

Switch - Coolant Level

D-10 I-12

B 34 36

150

RD

Hyd Lo Lock SW SW/ Hy Hyd Lock So Sol

Coupler Engage Sal

PU

Coupler Disengage Sal

GN

Eng Speed Cant. Hi Press SW

154

RD

A ux Ckt

788

YL

EngSpeed(+)

168

RD

Aux Ckt

791

PK

Eng Speed Cont. Lo Sol

172

RD

A ux Ckt

176

BU

A ux Ckt

Electronic Pump C ont Throggle G round Electronic Pump C ant Eng Speed G round

Aux Ckt

A768

BU

A769

GY

BU

lnsp Lamp

A770

PK

Electronic Pump C ont Bypass SW To R esistor  

PK

A ux Ckt

A771

PU

F loat SW

200

BK

GroundCircui ts

C

WH

B ackup SW

B

2 0 1

B K

Conv ert reO tu u p (t 4 2/ 2 1 Vol )t

F 73

OR

Go vern ro Ac cel

F-2

B

235

BK

Electronic Pump Ctrl Gnd

F774

WH

Governor D ecel

306

E-8

D

I-10

Relay -H -Hyd L ock Solenoid

I-10

Relay - Main

G-10

Switch - Pressure

D

I-7

Switch - Prox

D

I-7

Switch -R -Refrigerant Low Press

7

Switch - Refueling (Atch)

A-5

40

F-7

D

Relay -R -Refueling 1(Atch)

A-3

23

Switch - Refueling S top A ( tch)

A-4

41

Relay -R - Refueling 2( 2(Atch)

A-3

23

Switch - S eat Heater A ( tch)

D-4

B

Relay - Start

F-8

D

Switch - Start Aid (Atch)

D

F-8 F-7

D

Resistor - B ackup

I-11

24

D-5

Switch -S -Start Aid Coolant Temp A ( tch)

D

Relay - Timer

A-4

39

B-11

Switch - Key

E-2

41

B

F 84 6

PU

L ED D irve r 1

GN

Starter Rel ay C oi l

G848

GN

LED Driver 2

O R

K ey SW SW To To Ne ut ar l S t ar S t W

G 87 2

PU

E sp ar Ca bH bH a e et rt oP oP ow e r Sw ti ch

YL

Mai n Power Relay Coil

BasicMachine Circuits

952

OR

Hammer SW B

310

PU

320

OR

MonitoringCircuits

21

G-6 G-6

F F

CONN 16

G-6

CONN 17

H-6

CONN 18 CONN 19

H-6 H-5

CONN 20

G-5

F

CONN 21

F-5

B

CONN 22 CONN 23

F-5 F-5

B B

O p r Mo nO li P er s . L( ow Se tt ni g)

K 91 1

PK

E JP Co n t or ll er - R S 4B S( S( +)

BU

OprMon Cool Flow

K912

GN

E/P Controller -RS4BS -()

430

BU

Opr M on Air Filter

K915

GN

Fi e n Swing SW -E -E/P Controll re  

OR P K G Y

F-5

B 24 F

CONN 27

C-4

CONN 28

C-4

F

CONN 29 CONN 30

A-4 A-4

23 7

CONN 31

A-4

7

CONN 32 CONN 33

F-4 F-4

B B

F-4

B

CONN 35

H-4

C

H-3 H-3

C C

CONN 38

H-3

C

CONN 39

H-3

C

CONN 40 CONN 41

H-3 A-3

C 7

CONN 42

B-3

9

CONN 43 CONN 44

B-2 H-2

9 C

CONN 45

H-2

C

H-11

D

+V Sensor, EMS-Il

OR

Con rt loel rRS 2-3 C 2 Tx

BU

Cn o rt o l el rR S -2 3 2C Rx

L 6 9 8

OR

O p r MO nP an e l Hy Hy dO dO li Le Le ve l

L9 69

WH

E el ct or ni c P um p Co nt ar lP sV sV al ve (+ )

WH

Press.Transducer1Signal

L970

GY

ElectronicPumpCantToSWCommonReturn

El ec ro t in cP cP m u p Co tnor P l sV sVa vl e(. )

 A425

YL

Press.Transducer2Signal

L971

GN

ElectronicPumpCantToTravelPressureSW

C468

BU

Engine Oil Level

L972

BU

Low Idl e SW

506

PU

Washer-Front

508 5 9 0

L 9 73

GN

F i ne S wni g C n o t R lea y T o S o l V al v e

L974

GN

Electronics Pump C trl Boom Raise Press SW

PU

Radio Speaker -Left

WH

Rad oi Spe k a er -L -Lef t(Co m mom )

511

BR

Radio S peaker -Right

L978

GY

Level Finish Sol

5 12

G N

Rd a oi Sp ea ke .r Ri gh t( C om m on )

N9 23

G Y

Bc a ku pM d o eS eS wi ct h1 h1

5 19

PK

T he m r os at tT o R e rfgi er a n tP er s . S W

N9 24

WH

Bc a ku pM d o eS eS wi ct h2 h2

5 24

BU

W pi er - Le tf ( Lo w)

L975 L 7 9 7

PK

Start Aid C ont Lamp 1O 1Output

YL

T ern chi ng So l

Harness And Wire Electrical Schematic Symbols

17

F

Component Description

3E-1906

Solenoid: A/C Clutch

3E-6332

Solenoid: Valve Start Aid

4 I 5- 39 4

Sen d er : H yd a r ul i c Oi l T em p

7Y-8242

Resistor: Timer Relay

8C-3663

Solenoi d:EngineShutdown Start(Latch)Coil Stop(Unlatch)Coil

Resistance (Ohms) ¹

121-1491

RealTime ErrorCodes

6.00 20824-25415@0°C 6134-7496@25°C 3989-4875@35° C 2224-2718@50°C 973-1189@75°C 475-522@100°C 221-269@125°C 47.0 ± 4.7 1.55±0.1510.3±1.03 52.0 ± 2.6

Solenoid :Engine/PumpContro :Engine/PumpContro l FlowControl Solenoi d:LevelFinish Trenching Solenoid :AC1 :AC1 AC2 Hydrauli cLock Swing Brake TravelSpeed

121-1490

11,7±1.2 32.0±3.2

32.0±3.2

¹At roomtempera tureunlessotherwis tureunlessotherwis enoted. enoted.

13 D

3 15 21 14 2 30

11

27

34

38

39 29 E

6

20

26 33

12 F

Part No.

17

8 19 23 7

Function

Actuate

Deactuate

38±3°C (100±5°F)

27”CMm (80.6°F)

Contact Position NormallyClose d

3E-6449

CoolantTempe rature(StartAid) rature(StartAid)

3E-6 4 55 455

Engi neOilPressu e ssu re re

90 21 kPa (13±3.0psi)

70 ± 21 kPa (10±3.0psi)

 A-BNormallyOpen  A-CNormallyClosed

106-0179

Implemen tPressure tPressure TravelPressure

1520 ± 98 kPa (224.4±14.21psi)

1127kPaMIN (163.5psiMIN)

NormallyOpen

106-018 0

BoomRaisePre ssure ssure

2646.00±196.00kPa (383.77±28.43psi)

2156.00±196.00kPa (312.70±28.43psi)

114-533 3

Refrigeran tPressure(AC) tPressure(AC)

131-920 3

AuxHydraulicPressu re re

17 41

40

Off Machine Switch Specification

12

B

16 9 16

28 32

5 25

1

C

 A 10

35

22 18

1 2

NormallyOpen

275to1750kPa¹ (40to255psi)

— —

NormallyOpen²

3500kPaMAX (507.6psi)

3000 ± 150 kPa (435.1±21.8psi)

 A-BNormallyOpen  A-CNormallyClosed

¹A hysteresisban dexists:withincreasingpressu dexists:withincreasingpressu retheclosedconditioncanbemainta retheclosedconditioncanbemainta inedupto2800kpa(405psi),withdecreasingpressu inedupto2800kpa(405psi),withdecreasingpressu retheclosed retheclosed conditioncanbemainta ineddownto170kpa(25psi). ineddownto170kpa(25psi).

Theconnector sshowninthischartarefor harnesstoharnes sconnectors. sconnectors. Connecto rsthatjoinaharnesstoa compone rsthatjoinaharnesstoa ntaregenerallylocate ntaregenerallylocate dator nearthe dator compone nt.Seethe Compone nt.Seethe ntLocationChart. ntLocationChart.

²Contactpostionatthecontactsoftheharnessconnector.

Machine Harness Connector and Component Locations

Code 1 3 01 1302 1303 1 3 04 1 3 05 2201 2202 2301 2302 2 3 03 2 3 04 3 2 01 4101 4102 4103 4104 4105 4106 4107 4108 4109 410A 410B 4 2 01 4202 4203 4204 4 2 05 4 2 06 4207 4 2 0A 420B 420C 420D 420E 4301 4302 4 30 3  A201  A202  A203

Description of Problem s E n gi n e olip r e ss u re i s t o o l ow . Enginecoolanttemperatureistoohigh. Hydraulicoiltemperatureistoohigh. e istoohigh. A i r if l et r i s c l og g ed . B a tt e yr v o l at g e i s n ot n o rm a .l Governoractuatorfeedbacksensorcircuitisopenorshortedtobatteryvoltage. y voltage. Governoractuatorfeedbacksensorcircuitisshortedtobodyground. Governoractuatorfeedbacksignalisnotstable. Governoractuatorfeedbacksignaldeviates. G o ve r no r a c ut a ot r d o es n o t m ov e . C a il b a r toi n d a at e r r or . M o ni t or R A M i s n ot n o r ma l . Electricpowersupplytothecontrolleristoomuch(43volts). Over-currentinproportionalreducingvalve. Proportionalreducingvalvecircuitisopen. Monitorpowersupply(digitaloutput)overcurrent. n t. Over-currentindigitaloutput(trenchingsolenoid). Over-currentindigitaloutput(finecontrolsolenoid). Over-currentindigitaloutput(travelspeedchangesolenoid). Over-currentindigitaloutput(travelalarm). Sparesolenoid1(digitaloutput)overcurrent. Over-currentindigitaloutput(swingbrakesolenoid). Sparesolenoid2(digitaloutput)overcurrent. E n gi n e s pe e d i s n ot n o r ma l . Enginecoolanttemperaturesensorisshortedtobodyground. Hydraulicoiltemperaturesensorisshortedtobodygrou e sensorisshortedtobodyground. PWMsensorofpumpdeliverypressureisshortedtobodyground. S p ar e P W M se n so r 1 i s s h or t ed t o b o dy g r o un d . S p ar e P W M se n so r 2 i s s h or t ed t o b o dy g r o un d . PWMsensorofpumpdeliverypressureisopenincircuit. F u el s e n so r i s s h or t ed t o b o dy g r o un d Fuelsensorisopenorshortedtobatteryvoltage. y voltage. Electricpowersupplyistolow(below23volts). Electricpowersupplyistohigh(above32volts). Enginespeeddialisnotinoneofthe10specifiedpositions. Datamismatch1betweenalternatorandspeedsensor(alternatorisabnormal). Datamismatch2betweenalternatorandspeedsensor(speedsensorisabnormal). E ng n i e s at l s. Monitorcommunicationis notnormal. Monitortakestoo muchtimeto respondto controller'ssignal. Communicationisabnormal incontroller.

1 2

Typical representationof a Deutschconnector.The plugcontainsall sockets and thereceptaclecontains all pins.

Receptacle

Plug

17.6 ± 0.6

Resistor: Backup

111-9916

24

AA

Resistor,Sender andSolenoidSpecifications Part No.

102-8017

4

Printed in U.S.A.

1

9

40 28 15 30 11 D 24 32 E 5 25 6 10 3 4 27 1 26 41 34 20 23 36 16 8 2 29 C 7 38 B 13 33 18 22 19

36 31

©2000 Caterpillar   All Rights Reserved

 A

35 39

F

CONN 36 CONN 37

L 90 9

VMI SF uel Le e v lSi gna l

WH

AccessoryCir cuits

12

BU

L 0 9 8

VM I SC SC o al n t Te Te m p Se Se n s or Si gn al

GN

4 96

F F

C-5 C-5

CONN 46 SIS Connector

K997

VM SI H y dO li Tem pS n e sor

4 5 9

 A424

F

CONN 25 CONN 26

CONN 34

Hyd Oi l Fl ow SW

No circle indicates thatthe wire cannotbe disconnected from the component.

This indicates thatthe componentdoes nothave a wire connected to ground.Itis grounded by being fastened to the machine.

G Y

412

F

CONN 24

S wi n g Br a ke S o l - +8 Backup SW +8

GN

4 05

D 1

C-6

RU BU

403

39 A

 A

CONN 14 CONN 15

K97 0 K909

B

D-10

4 92

The circle indicates thatthe component has screw terminals and a wire can be disconnected fromit.

This indicates thatthe componenthas a wire connected to it thatis connected to ground.

Swi ng Bra ke So l- Si gnal

Alternator (R) Term.

Normally closed switch thatis open due to an applied condition,and will close again with a specific decrease in thatcondition.

7JR1-UP 1XS1-UP 2AS1-UP 5MS1-UP 9WS1-UP 6LW1-UP 3YZ1-UP

HammerSWA

Pm u pD pD si ch ra g e - Si gn a l Pump D ischarge. +B

GN

24

Normally closed switch thatwill open with an increase of a specific condition.

Hammer Sol A

G N RD

K 0 96

B-7

14

CONN 13

RU

K 90 4 K905

Ai rS u h ot ff So eln io dE dEn b a el

487

31

GN

955

Bc a ku pA pA al m r La m p Tr Tr v ae l A al m r Key SW "C" Term.

P K

4 1 9

ConnectorLocation

D

954

Horn Rel ay C oil To SW

BR RD

3 6 8

Switch - Travel Press

21

D

Start A i dSW To Start Aid Sol

3 21 326

Switch - Windshield

E98059

29 E

F772

3 07

H = Located inside dash.

29

Main Chassis

308

39 24

Relay - Neutral S tart

E-8

Switch - Refueling Start A ( tch)

C-11

F = Located around pilot manifold.

I-7 A-6

Bc a ku pS W

39

H-4 D-4

G = Located under platform.

I-7

O R

D-10

E =Located around hydraulicoil tank.

F-9

F 77 1

Pump Control Valve #2 (-)

Switch - Neutral Start Limet

D = Located around relay panel.

G-11 A-11

Pump Control Valve #1 (+)

Aux Ckt

196 198

Switch - Overload Warning Device O.W.D.

B = Located inside of right console.

G-11

Throttle SW #4

PU

Switch - Panel

D

C = Located inside of left console.

CONN 11 CONN 12

T hrottle SW #3

PU

A762

D

 A = Locate d insideof cab.

CONN 9

T hrottle SW #2

GY

A761

Aux C kt

RD

Machine locations are repeated for components located close together.

CONN 10

Throttle SW #1

BU

A758

Aux C kt

YL

D

A-3

Relay -S -Start Disable

CONN 6

PK

BR

A757

Main Brkr

BN

I-10

Relay - Heater

CONN 7 CONN 8

A756

Aux Ckt

RD

180 185

I-10

Relay - Horn

D

A755

YL

177

WH

Flow Symbol

Normally open switch thatis closed due to an applied condition,and will open again with a specific decrease in thatcondition.

320B Excavator  Electrical System

176

191

Level Symbol

Normally open switch thatwill close with an increase of a specific condition (temp-press-etc.).

ControlCircuits WH

780 786

Relay - Boom Lamp Relay - Fuel Heater

D

779

Aux Ckt

Relay - Cab/Chassis Lamp

Pump - Refueling

D

Torque Converter SW

Aux Ckt

189

Switch - m I plement P ress

R otary Beacon

BU

BN

33 E

Attach Lighting Ckt

WH

BU

38

Temperature Symbol

Bucket Flood a Lmp/Boom Flood a Lmp

BU

638

763

151

B-11

E

A ux Ckt

152

Switch - Engine Oil Press

A-5

BU

BoomL amp

D

D-4

616 633

F l ow C on tF/ i ne S wni g S ol e no i d

PU

18

A-5

Aux C kt Lubricator

BU PU

149

I-11

Switch - Hyd Oil Filter

Pressure Symbol

LightingCircuits

145

A-11

Switch - Hyd Oil Level

D

35

A/C

147

Switch - Engine Oil Level Switch - Swing Control

7

D-7

D-2

Switch - Boom Raise Press Switch - Disconnect

D

H-12

Pump - Heater Fuel (Atch)

Switch - Backup

A

C-7 A-11

Motor -Lower Wiper

H-12

T

Safety So Sol Re Relay To To So Sol

B-11

D

D D

GN

Aux Hy d. Cl s o e

Washer/Wiper

YL

Solenoid - Fine Swing

23

F-12

A588

P ow re Wi nd ow Co n t T oS af et y S olR e al y

PK GY

120

Solenoid -Engine S hutdown

B-7

F-12

B R YL

115 118

Solenoid - Flow Control

A-3

H-11

58 6 A 58 7

Cab/Chassis Lamp

Electrical Schematic Symbols And Definitions

15

I-12

G-12 G-12

Wiper.Aux(Low) Washer.Aux

2

Ground - Chassis

CONN 5

PK BU

33

Ground - Cab

CONN 3 CONN 4

576 576

C-6

Ground - Chassis

CONN 2

Main Power Rly O utput

H-9

SEN R3581

CONN 1

A ux Ckt

E-2

SENR9291

Machine Location

575

RD PU

Aux Hyd - Rotate CCW A ux Hyd - Open

Convertor

SENR9292

Schematic Location

Alt Output(+) Term.

111 112

A ux Hyd - Rotate CW

Controller -A -Aux/Hyd (Atch)

Starting and Charging:

ConnectorNumber 

B at(+)

Controller - E ngine/Pump

Engine/Pump Control:

SENR9278-03 March2000

Description AccessoryCi rcuits(Continued)

546

D-7

F-9

D-8

Wire Wire Number  Color 

Description PowerCircuits

101

5

I 1-1

Fuse - Block

ElectricStartingMoto r:104-7040 r:104-7040 Cons si :t 6V- 5 821

Machine Location E

B-11

A-5

Breaker -Fuel Heater

Control - Wiper

Form Number 

Schematic Location F-4

Br e aker -Al et r n at o r Breaker - Main

Title

Component Seat W/Sea t Heater (Atch )

Block - Terminal

Breaker -Warming Windshield

RelatedElectrical Service Manuals

Wire Description

Schematic Location H-4

 Alarm-Travel(Atch)

 A/CUnit

2

Typical representationof a Sure-Sealconnector.The plugandreceptaclecontain bothpins andsockets.

Pinor Socket Number  Wire, Cable,or Harness  AssemblyIdentification

Component Part Number 

Single Wire Connector  C

 A

A 325-PK-14

Pin

AA 1

9X-1123 325-PK-14

Wire Color 

Socket

2

200-BK-14

CircuitNumber  Identification

Wire Gauge

ElectricalSchematic Symbols And Definitions FUSE -A componentinanelectrical circuitthat will openthecircuit iftoo muchcurrent flows throughit. REED SWITCH -A switchwhosecontactsare controlledbya magnet. A magnetcloses he t contactsof anormallyopenreed switch; it opensthecontacts ofanormally closedreed switch.

T

SENDER -A componentthatisused witha temperatureor pressuregauge. Thesender  measuresthetemperatureor pressure. Itsresistancechangesto giveanindicationto the gaugeofthe temperatureor pressure.

RELAY (Magnetic Switch) - A relayis anelectrical component that is activated by electricity. It hasa coil that makes anelectromagnetwhencurrentflows through it. The electromagnet canopenor closethe switch part oftherelay. CIRCUITBREAKER(C/B) - A componentinanelectrical circuit thatwill openthe circuit if too muchcurrent flowsthroughit. Thisdoesnotdestroy thecircuitbreakerand it canbereset to become part of thecircuitagain. SOLENOID-A SOLENOID -A solenoidis anelectrical component that is activated ated by electricity. Ithas acoil thatmakesan electromagnetwhencurrentflowsthroughit. Theelectromagnet canopen or  closeavalve or move apieceof metal thatcando work. MAGNETIC LATCHSOLENOID -A magnetic latchsolenoidis an electrical componentthatis activatedbyelectricityand held latch bya permanent magnet.It has twocoils(latch and unlatch) thatmakeelectromagnet whencurrentflowsthroughthem. Italsohas aninternal switchthatplaces thelatchcoil circuit openatthe timethe coil latches.